Cluster 2/FM5 (Rumba)

NSSDC/COSPAR ID: 2000-045A

Description

This Cluster II spacecraft, FM5 (Rumba), is also known as Phoenix, after a mythical Arabian bird which was burnt on a funeral pile and then rose from the ashes to live again. The original Cluster of four spacecraft experienced a launch failure in 1996. (NSSDC will carry the name "Cluster96" in its information files to designate the unsuccessful 1996 four-spacecraft Ariane 5 launch.)

Phoenix was approved in July 1996 as a replacement for the lost four-spacecraft group. It was later (April 1997) agreed that the potential science return from a full Cluster reflight was so important that a further three near-replicas of the original spacecraft would also be built.

This Cluster II spacecraft, FM5 (Rumba), was launched together with FM8 (Tango) by a Soyuz-Fregat rocket from Baikonur. The four similar spacecraft of the Cluster II mission are part of ESA's and NASA's Solar-Terrestrial Science Program (STSP). The purpose of the Cluster II mission is to study small-scale structures in three dimensions in the Earth's plasma environment, such as those involved in the interaction between the solar wind and the magnetospheric plasma, in global magnetotail dynamics, in cross-tail currents, and in the formation and dynamics of the neutral line and of plasmoids.

The four Cluster II spacecraft will orbit in a tetrahedral formation in near-polar orbits of nominally 4 x 19.6 Earth radii, with period about 57 hours, and inclination about 90.7 degrees. Relative distances between the spacecraft will be adjusted in the course of the mission, depending on the spatial scales of the structures to be studied, varying from a few hundred km to a few Earth radii. The tetrahedral formation is essential for making three-dimensional measurements and for determining the curl of vectorial quantities such as the magnetic field.

Each spacecraft will be spin-stabilized, normally at around 15 rpm, and will be cylindrical in shape, with a 2.9-m diameter and 1.3-m length. It will have two rigid 5-m radial experiment booms, four 50-m experiment wire booms, and two axial telecommunications antenna booms. Telemetry downlink bit rate will be 2 to 262 kbit/s.

Each spacecraft will have AC and DC magnetometers, an electric fields and waves sensor, an electron emitter/detector, an electron density sounder, electron and ion plasma analysers, an energetic particle detector, an ion emitter, and a data processing unit.

Cluster operations will be performed by ESOC in Darmstadt, Germany, with support from NASA's Deep Space Network. Cluster is also an IACG mission. The scientific data are distributed by ESOC using CD-ROM as a medium to the Principal Investigators, Co-Investigators and the network of eight national data centres (6 in Europe, 1 in USA and 1 in China) that form the Cluster Science Data System (CSDS). There are approximately 80 recipients world-wide. Science operations are carried out by the Joint Science Operations Centre, co-located with the UK data centre at RAL, Didcot. A wide scientific community will have differing rights of access to the Cluster data. Scientists wishing to access Cluster data should contact their national Data Centres.

An article on 'The Resurrection of the Cluster Scientific Mission' was published in ESA Bulletin no. 91 (August 1997).

A complete overview of the original mission, written before the loss with Ariane-5, was given in a series of articles in ESA Bulletin no. 84 (November 1995).